Setting a standard for prosthetics

By Michael Souza PBN Staff Writer

Thanks to the work of Brown University associate research professor in public health Linda Resnik, a new method of evaluating the effectiveness of a prosthetic upper limb is in the making. While it’s too early to tell, the new process could become a standard by which doctors define the progress of patients and their use of prosthetics. More

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Focus: HEALTH CARE

Setting a standard for prosthetics

Posted:
Saturday, December 1, 2012 12:05 am

By Michael Souza PBN Staff Writer

Thanks to the work of Brown University associate research professor in public health Linda Resnik, a new method of evaluating the effectiveness of a prosthetic upper limb is in the making. While it’s too early to tell, the new process could become a standard by which doctors define the progress of patients and their use of prosthetics.

The new method developed as a result of the United States having fought wars on two fronts, causing a dramatic rise of those with an amputated upper limb. Because of advances in emergency response and medical science, many soldiers lived when in past wars they would have died.

What’s left is that amputees with a new prosthetic arm must learn how to use their device to perform the simplest everyday tasks that were always taken for granted. Tying shoes, buttoning shirts and using utensils, once second nature, become arduous struggles.

Patients usually work with a team of doctors, therapists and prosthetists to help learn how their new limbs can provide some semblance of function. Unfortunately there has not been a standardized method to measure their success or lack thereof. But that may soon change.

Resnik is an associate research professor and a prosthetics research director at the U.S. Department of Veterans Affairs new Center for Neurorestoration and Neurotechnology in Providence. In the past, some of the parameters that were evaluated were performed in a less-than-scientific manner, for example, observing one’s opinion of progress on a scale from one to 10. However, the method could be prone to error by a patient inadvertently compensating or could vary based on factors such as tolerance to pain. Another problem is that two or more doctors could make differing judgments on a patient’s progress.

Resnik’s research team has established a new index that clinicians can use to assess their patients’ progress in adapting to the use of prosthetics. The system, called Activities Measure for Upper Limb Amputees, was published in the October “Archives of Physical Medicine and Rehabilitation,” an online magazine.The AM-ULA provides unified, standard criteria for clinicians to measure a patient’s performance in 18 everyday tasks, including serving soda from a can, dressing and removing a shirt, combing hair, tying shoes and using a spoon. These everyday jobs require varying amounts of speed and skill. While some might consider them ordinary, they can also be difficult tasks patients need to relearn in order to become independent.

“It is a measure” of progress, Resnik said. “When amputees are given the test and all the different tasks, they are graded. The scores are calculated and people are assigned a numerical score at the end.” The measure is specifically designed for upper-limb amputees.

“There are measures in existence for lower-limb amputees,” Resnik said. “This is for the upper limbs because it focuses on functional tasks that we normally perform with our hands and arms.”

When it came time for testing of the methodology, 49 veterans at VA facilities in Tampa and New York, and the U.S. Army’s Fort Sam Houston in Texas were examined, and the results showed the metric was effective.

“Much of the credit also goes to the U.S. Department of Veterans Affairs,” Resnik said. “We could not have done it without them. They provided help, as well as funding for the study.”

A standard of measurement is necessary and becoming more so because of the rise in technology. In myoelectric prosthetic devices, the arm is controlled by electrical impulses generated by the muscles in the residual limb. There is an increasing amount of prostheses available [with] multiple grips and wrist movement.

“On the projects that I’ve been working on, the capabilities of devices under development are even greater. We expect that amputees will be able to perform more functions with these more- sophisticated devices,” she said.

Most amputees use body-powered devices. It’s the most popular device and has been in existence since the 1940s. They normally operate using a cable system where a harness is worn across the shoulder blade; the amputee must learn to squeeze their shoulder, thus opening and closing the terminal device of the hook.

The measurement system was developed as part of a study of an advanced upper-limb prosthesis.

“We needed a good measure to use in the study but there wasn’t any,” she said. “This measure was developed and tested. We used it later in our study of the DEKA arm [made by DEKA Research of Manchester, N.H.] and we’ve continued to use it for other studies.”

One of the key methods of refining the metric was whether two independent raters, observing the same patient performance, arrived at the same ratings. Researchers also validated the measure by making sure that the results were clinically progressive. Scores were highest for people with amputation of the hand, lower for those with amputation above the elbow, and lowest for amputees with amputation at the shoulder. The team also analyzed statistics to calculate overall change. For example, a patient whose scores change more than “3.7 points” is likely to have truly changed, as opposed to an errant result.

As for now, the metric will continue to be used for additional research. Whether it will ever be used on a national level remains to be seen.

“We hope to distribute it so that other clinicians can use the measure to help them in decision-making and tracking the progress of patients,” she said. “There’s a lot of work under way to reach a [national] consensus to see what types of measures should be used.” •

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